Instruments used in medical interventions like minimal invasive surgery are increasingly equipped with one or more sensors that transmit data from inside the body. A cardiovascular catheter has for example been described that comprises a pressure sensor, wherein an external clock signal is provided to this sensor to allow for a digital data communication (Jin Ji et al., “An Ultraminature CMOS Pressure sensor for a multiplexed cardiovascular catheter”, IEEE transactions on electron devices, Vol. 39, No. 10, Oct. 1992).